Printer controllers face difficulties when they have to send print data to two or more printhead modules in a printhead, each of the modules having one or more rows of print nozzles for outputting ink. In one embodiment favored by the applicant, data for each row is shifted into a shift register associated with that row.
The applicant has discovered that some manufacturing advantages arise when printhead modules of different lengths are used within a product range. For example, a particular width of printhead for a pagewidth printer can be achieved with various different combinations of printhead module. So, a 10 inch printhead can be formed from two 5 inch printhead modules, a 6 and a 4 inch module, or a 7 and a 3 inch module.
One difficulty that arises is supplying data to one or more printheads or printhead modules at a sufficient rate and in the correct order.